河西走廊东部积雪的时空演变特征分析

利用河西走廊东部5个气象站1961—2007年近47 a的逐月积雪深度和积雪日数的常规观测资料,分析河西走廊东部最大积雪深度和积雪日数月、季节和年的空间分布以及时间变化特征。结果表明:受海拔高度、地理位置以及天气系统等影响,河西走廊东部积雪日数、最大平均积雪深度和极端最大积雪深度的分布从东南向西北递减,高海拔地区多于低海拔区,山区多于平原区。时间变化上,积雪日数47 a来呈平稳变化趋势,震荡减少,变率很小,积雪深度呈增加趋势;河西走廊东部积雪日数最多出现在1月,最少出现在9月,积雪深度最大出现在3月,最小出现在12月;积雪日数冬季最大,春季次之,秋季最小;积雪深度春季最大,秋季次之,冬季最小;相关系数法分析表明,积雪日数和积雪深度都是冬季的变化主导了年尺度的变化;河西走廊东部积雪日数1990s中期以前以6~7 a、9~10 a和2~3 a的周期为主,1990s中期以后周期主要表现为6~7 a和2~3 a;积雪深度1970s中期以前以6~7 a和2~3 a周期为主,1970s中期~1990s中期9~10 a、12~13 a和2~3 a反应明显,1990s中期以后周期又表现为6~7 a和2~3 a。

Characteristics of temporal and spatial variation of snow covering days and depth in east of Hexi Corridor

The temporal-spatial distributing characteristics of snow cover were analyzed based on the conventional observation data of monthly snow cover days and depths of 5 stations in east of Hexi Corridor stations from 1961 to 2007,The results show that in the spacial structure,because of altitude,geographical position,influence system,the distribution of snow cover depth and days decreasing from southeast to northwest,the number of snow cover days and depth in high altitude areas more than in low altitude areas,in mountain stations more than in plain;in the temporal chang,there is a decreasing trend in the observations on snow cover days and an increasing trend on snow cover depth,the maximum and minimum snow cover days occurrs on january and on september,the maximum and minimum snow cover depth occurrs on march and on december.In seasonal changes,the maximum number of snow cover days occurs in winter,second in spring,the least in autumn,the maximum of snow cover depth occurs in spring,second in autumn,the least in winter.On the attribution,the trends of snow cover depth and days in winter was the most important in annual change.It is found that the vibration periods of 6～7 a,9～10 a and 2～3 a are displayed very clear of snow cover days before the mid-1990s and the vibration periods of 6～7 a and 2～3 a are displayed very clear behind the mid-1990s.and also found that the vibration periods of 6～7 a,9～10 a and 2～3 a are displayed very clear of snow cover depth before the mid-1970s and the vibration periods of 9～10 a,12～13 a and 2～3 a are displayed clear from the mid-1970s to the mid1990s,the vibration periods of 6～7 a and 2～3 a are displayed very clear behind the mid-1990s.